CNC machines often combine multiple tools (e.g. lathe and mill) into a single ‘cell’, and can be expensive pieces of equipment. There is thus a significant motivation to optimize yield of existing machines in a production plant prior to considering the acquisition of an additional machine. These machines are often operated on three shifts and efforts are made to limit the amount of downtime during each shift.
Apart from normal maintenance operations and repairs, downtime is also present during the step of removing the machined part from the machine and positioning a subsequent part thereon. To address this latter form of downtime, it was known to use specialized equipment referred to as ‘pallets’ which can be mounted and dismounted to the CNC machine faster than the amount of time it would take to correctly mount and dismount the part itself from the CNC machine. With more than one pallet made available for any given CNC machine, the operator can mount the next part in the production line to a corresponding pallet while a part is being machined by the CNC machine, and the pallets can then be interchanged as soon as the machining is completed.
This latter system reduced downtime and improved machining efficiency. However, in the case of CNC machines having a lathe, the operator still had to center the part on the automatic machine tool. There thus remained room for improvement.